When Valley Stream firefighters responded to a commercial fire on Hawthorne Avenue last year, it set the stage for the uncovering of a multi-million-dollar counterfeiting operation.

A small fire last year at a Valley Stream warehouse led to the takedown of an alleged multi-million-dollar health and beauty product counterfeiting operation, and the arrests of its two leaders.

Nassau County District Attorney Kathleen Rice announced the arrests last Friday, a day after prosecutors seized four tractor-trailers full of products while executing a search warrant at five locations. Rice said the operation was brought to the attention of her office by fire officials.

According to Rice, brothers Hamant Mullick, 60, of Franklin Square, and Pardeep Malik, 59, of Plainview, ran a “sophisticated” operation in manufacturing, storage and showroom facilities in Franklin Square, Oceanside, Valley Stream and Freeport. The two men, Rice said, sold products to distributors that they and at least 20 of their employees manufactured that closely resembled those of major international companies such as Johnson & Johnson, Pfizer, Procter and Gamble, and Unilever. Counterfeit ChapStick, Vicks VapoRub and Vaseline were found in retail locations in New York, Pennsylvania and Florida. An investigation is under way to determine whether retail outlets in any other states sold the brothers’ manufactured products.

The investigation of the operation began in January, after Valley Stream Fire Department officials returned to the site of a March 2013 fire — which involved burning boxes of what was then thought to be Vicks VapoRub at an industrial building on Hawthorne Avenue — for a routine follow-up inspection, and noticed suspicious items such as gas piping and open burners filled with wax. Officials from the Nassau County fire marshal’s office then searched the building and found some of the bogus products, which they later sent to the legitimate manufacturers, who verified that they were counterfeit.

Inside the building, Fire Marshal Scott Tusa said, investigators found “numerous fire and code violations, including open electrical wiring, empty fire extinguishers, and locked and blocked exits that made the workers inside virtual prisoners in the event of a fire or other emergency.”